Chungkookjang and Natto are representative fermented foods and are produced by fermenting soybeans using Bacillus subtilis. When soybeans are fermented, γ-polyglutamate and polyfructan polymers are generated. γ-polyglutamate is known to have moisturizing and cell activation functions, and when used together with an anti-cancer drug such as Taxol, the effect of the drug used is increased. Polyfructan is a dietary fiber that is used to lose weight and when administered, gastric fullness and appetite suppression can occur and thus, obesity can be prevented. In addition, it is reported that polyfructan inhibits growth of harmful cells in bowels and helps Bifidobacterium grow (see Journal of Applied Microbiology, 92, 5, p 958-963).
Patents related to fermented soybeans include a patent related to a cosmetic material (see Korean Registration Patent No. 0451631), and a patent related to a skin external application (see Korean Publication Patent No. 2001-0083876). Seong mun-hoe et al. developed an enzyme-based technique for producing γ-polyglutamate having a molecular weight of 2,000 kDa or more (see App. & Environ. Microbiol. 2004; 70(7), 4249-4255; and Korean Registration Patent No. 10-0399091). Also, they registered a patent based on research results regarding a material in which an ascorbic acid binds to γ-polyglutamate having such a high molecular weight (Korean Registration Patent No. 10-0485727). However, a novel type of fermented soybean polymer in which a folic acid (also called as vitamin B9) binds to γ-polyglutamate and an application thereof have not been developed.
Folic acid is known to be a material that lowers levels of homocysteine that is associated with heart disease and dementia of elderly people. Accordingly, when folic acid is used in foods for elderly people, high effects can be obtained. Folic acid naturally exists in a polyglutamate form and thus can be easily absorbed into bodies of animals and humans.